The “Black Panther” star was spotted turning up with his rumored GF, Ashlyn Castro, at the ritzy VIP Room nightclub in St. Tropez. It got real steamy in the club … and it had nothing to do with Mike’s cigar.

Check out the pics … MBJ — who, btw, is rocking a sweet Elvis tee — and Ashlyn were all over each other … grinding, sucking face and living it up. Just like you-know-who.